Blockstream executives say they'll finish building sidechains within a few months. Greg Maxwell, the company's CTO, told MiningPool that his team expects to deliver a new version within two months, w
Blockstream executives say they'll finish building sidechains within a few months. Greg Maxwell, the company's CTO, told MiningPool that his team expects to deliver a new version within two months, with additional work needed on compact SPV proofs, a key mechanism described in the original sidechains white paper.
The sidechains concept first surfaced in April 2014 during the 99th episode of Let's Talk Bitcoin. Two years later, developers still haven't deployed a finished version on Bitcoin's mainnet, though Blockstream's Elements Alpha offers a testnet for the technology. Maxwell explained that Elements Alpha "uses the full sidechains mechanism in one of the two peg directions, though not with compact SPV proofs."
Blockstream's next step involves completing work on the optimal design parameters for compact SPV proofs. Once that's finished, the company plans to release a Bitcoin Improvement Proposal with reference code for public review and feedback. The National and Kapodistrian University of Athens recently published a research paper validating Blockstream's approach to the technology.
Other teams are pursuing sidechains. Paul Sztorc at Bitcoin Hivemind has written about drivechains, a different model, and Rootstock described a hybrid approach combining elements of both. Maxwell noted that "The technical community has been supportive of the concept of sidechains as a framework for independent development of interoperable bitcoin denominated chains." A Blockstream representative declined to comment on the drivechain idea, saying it was premature, but Maxwell expressed interest in a zerocash sidechain and other innovations. Zcash, the non-Bitcoin version of zerocash, launches this summer.
The main value of sidechains is testing. They let developers experiment without risking the main Bitcoin chain. Segregated Witness, a major improvement arriving later this year, originated as a sidechain experiment. Maxwell also described a signature aggregation scheme he's been developing that could reduce transaction sizes by 30 percent, another candidate for testing on a sidechain.
Several sidechain projects warrant attention: Bitcoin Hivemind, Rootstock, the planned zerocash sidechain, and another sidechain designed for testing Confidential Transactions, a privacy enhancement under consideration for Bitcoin.
